PB1937: A RARE, DIFFICULT- TO- DIAGNOSE DISEASE; LANGERHANS CELL HISTIOCYTOSIS – A SINGLE CENTRE EXPERIENCE
Authors: Betül Kübra Tüzün, Ajda Güneş, Derya Demir, Nur Soyer, Mahmut Töbü, Filiz Vural, Serra Kamer, Selen Bayraktaroğlu, Fahri Şahin, Güray Saydam
Journal: HemaSphere (2023)

Topic: 6. Chronic lymphocytic leukemia and related disorders - Clinical Background: Langerhans cell histiocytosis (LCH) is a rare, clonal disorder derived from CD1a-positive and CD207-positive immature myeloid dendritic cells, with a wide range of clinical presentations. Diagnosis of LCH is difficult and may be delayed due to its rarity and wide clinical manifestation. Aims: In this study;we aimed to retrospectively analyse our patients with LCH in terms of diagnostic procedure,clinical course and treatment outcomes fort he last 12 years. Methods:Results: Twenty-nine patients who were diagnosed with LCH and received treatment between January 2010 and September 2022 at Ege University Hospital (İzmir, Türkiye) were included. Overall, 18 patients were male (62%), with a male-to-female ratio of 1.6:1. The median age at diagnosis was 36 years (range,17-62 years). The median time from disease onset to diagnosis was 3 months (range 1–180months). After a median follow-up of 38-months (range 3–153 months), all patients are alive. At the time of diagnosis, 18 patients were classified as unifocal single system LCH (62,1%), 2 patients had pulmonary single system LCH (6,9%), 2 patients had multifocal single system (6,9%), and 9 patients had multisystem LCH (31%). Among the 18 patients with unifocal single system or organ, 14 had unifocal bone lesions, 2 had isolated pulmonary system, 1 had ear involvement and 1 had other single lesions (tooth). The most prevalent involvement in multisystem patients was the pituitary gland (66%), followed by the bone (55%), lung (55%), and vulva (33%). Ten (34,5%) patients had risky organ involvement. Seven patients (24,1%) had received systemic chemoterapy, 11 (37,9%) had radiotherapy and 5(17,2%)had both chemotherapy and radiotherapy as treatment. Therapies in this study were vinblastine and prednisone-based chemotherapy, cladribine monotherapy, lenalidomide, vemurafenib and radiotherapy. The ORR was 93%, including 23 patients (79,3%) classified as having CR and 5 patients (17,2%) classified as having PR. One patient (3,4%) were evaluated as SD. Three patients had reactivation of disease. One of our patients was diagnosed after 15 years, she had developed central diabetes insipitus. Summary/Conclusion: The clinical course and prognosis of LCH is diverse ranging from a spontaneously regressing single lesion to a life-threatening multisystem disease with rapid progression and death. Systemic evaluation is crucial because treatment decision depends on organ-tissue involvement. Treatment should be individualized and multi-disciplinary in order to reach good outcome. In conclusion, although adult-onset LCH is rare, it should be considered in a differential diagnosis in cases of central diabetes insipidus and spontaneus pneumothorax. Although LCH has been relatively benign disorder, it might result in complications potentially affecting vital organs. Keywords: Clinical outcome, Langerhans Cell Histiocytosis, Treatment